1. Field of the Invention
The present invention relates to a chronograph timepiece having a time indicating function and a time measuring function.
2. Description of the Related Art
There has been developed a multi-function timepiece in which a plurality of drive motors are mounted in order to individually drive a plurality of indicator hands to endow it with a time indicating function for indicating time information as a basic function and, further, with a chronograph measuring function for performing time measurement, wherein there are mounted a magnetic field detecting unit for detecting an external magnetic field around the motors and a rotation detecting unit for detecting rotation of the motors (See, for example, Japanese Patent No. 3,019,324).
In the above multi-function timepiece, the rotation detecting unit and the magnetic field detecting unit are mounted in a timepiece time motor drive circuit; when non-rotation is detected or an external magnetic field is detected, control is effected such that the driving is performed with a drive pulse (correction drive pulse) of higher power effective value than the normal drive pulse for normal drive; a chronograph drive pulse at the time of normal driving of a chronograph motor drive circuit effects driving at an interval shorter than a 1-second cycle; thus, in many cases, driving is effected at high speed drive timing; it is common practice to use a drive pulse of high power effective value in order to eliminate the need for the mounting of the rotation detection unit and the magnetic field detecting unit.
Here, in a case in which chronograph measurement is started with an arbitrary timing by the user and in which the chronograph drive timing for driving the chronograph indication motor and the magnetic field detection timing for the timepiece time motor drive circuit overlap each other, an erroneous magnetic field detection is effected under the influence of magnetic field generation due to the chronograph drive pulse, causing driving to be effected unnecessarily by the correction drive pulse; further, there is generated a deviation in the drive timing for the time indication motor due to the starting of the magnetic field detection of the time indication motor after the chronograph drive pulse.